Problem: $h(n)=63\cdot\left(-\dfrac{1}{3}\right)^{{\,n}}$ Complete the recursive formula of $h(n)$. $h(1)=$
$h( 1)=63\cdot\left(-\dfrac13\right)^{ 1}={-21}$ $h( 2)=63\cdot\left(-\dfrac13\right)^{ 2}={7}$ $\dfrac{h( 2)}{h( 1)}=\dfrac{{7}}{{-21}}={-\dfrac13}$ So the first term of the sequence is ${-21}$ and the common difference is ${-\dfrac13}$. This is the recursive formula of the sequence: $\begin{cases} h(1)={-21} \\\\ h(n)=h(n-1)\cdot\left({-\dfrac13}\right) \end{cases}$